target/i386: emulate: Make sure fetch_instruction exist before calling it

Currently, this function is only available in MSHV. If a different accelerator
is used, and the code jumps to this section, a segfault will occur.
(I ran into this with HVF)

Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Link: https://lore.kernel.org/r/20251114082915.71884-2-phind.uet@gmail.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/emulate/x86_decode.c b/target/i386/emulate/x86_decode.c
index 97bd6f1a3be9426e13d19552d3cae391e7ab60f3..d037ed114201a97bac97f6edd6cb59ded8790e73 100644 (file)
--- a/target/i386/emulate/x86_decode.c
+++ b/target/i386/emulate/x86_decode.c
@@ -77,7 +77,11 @@ static inline uint64_t decode_bytes(CPUX86State *env, struct x86_decode *decode,
         memcpy(&val, decode->stream->bytes + decode->len, size);
     } else {
         target_ulong va = linear_rip(env_cpu(env), env->eip) + decode->len;
-        emul_ops->fetch_instruction(env_cpu(env), &val, va, size);
+        if (emul_ops->fetch_instruction) {
+            emul_ops->fetch_instruction(env_cpu(env), &val, va, size);
+        } else {
+            emul_ops->read_mem(env_cpu(env), &val, va, size);
+        }
     }
     decode->len += size;